With the proliferation of smartphones, tablets, phablets, and other display devices, people have the ability to take or display digital images virtually any time. Smartphones and other portable display devices are commonly used for a variety of applications, including both business and personal applications. Certain application programs have become popular that allow users to modify images containing pictures of the user or other people. For example, devices may be used to capture or receive digital images (either still images or video images) containing an image of the user's face. The ability to add “fun stickers” is an increasingly popular feature in mobile applications, where a graphical effect or image (e.g., a sticker) is selectable by a user and able to be applied to the image.
To make this feature more interesting, an image (e.g., fun sticker) is often “stuck” onto a facial image in the digital image, where the position and orientation of the sticker corresponds to the position and orientation of the individual's face. For example, the sticker may be a crown placed on the head of the face shown in the image. The state of the art method for incorporating such fun stickers generally involves transformation and rendering. The head orientation is usually estimated by detected feature points to transform the sticker. However, the transformation process is often not precise enough (e.g., a crown sticker, which does not properly rest on the head of the image), which detracts from the “realism” of the coupling of the sticker with the facial image.
Therefore, it is desired to provide an improved method for implementing this feature, without imposing overburdened computations on the device.